This invention relates to gate valves and more particularly to gate valves of the expanding type which expand laterally at fully open and fully closed positions.
Expanding gate valves include a gate and a segment carried by the gate with relative longitudinal movement between the gate and segment effecting a lateral expansion of the gate valve. It is desirable that the gate and segment remain in a collapsed or contracted relation during travel between open and closed positions so that binding against the seats will not occur. Also, it is desirable to limit the movement of the seats toward the gate assembly so a minimum clearance is provided as the gate assembly moves between open and closed positions. So-called floating seats are oftentimes employed with expanding gate valves and various means have been provided to limit the floating movement of the seats toward the gate assembly. For example, U.S. Pat. No. 4,116,419 dated Sept. 26, 1978 discloses an arrangement for limiting the floating movement of the seats toward the gate assembly by the use of an L-shaped retainer. Other means have included flanges or shoulders on the seat supports for limiting the movement of the seats toward the gate assembly.